by Stephen A. Kallis Jr.
Like its relative, the movie serial, the adventure serial on radio was a
continuing story, generally with lots of action; Each episode ended with
the program's characters in an unresolved (and usually cliff-hanging)
situation, which would be resolved in the following show.
From the late 1930's through the early '50s there were lots of radio
adventure serials. They ranged from the famous, like "Jack Armstrong, the
All-American Boy", and Tom Mix and his Ralston Straight Shooters to the
obscure, like "Tennessee Jed" and "Speed Gibson of the International Secret
Police". Most were broadcast between 5 and 6 p.m. and were aimed primarily
at children.
One of the most popular of these was "Captain Midnight" a show sponsored
by Ovaltine. Although Captain Midnight was in the thick of the children's
hour, it was unique in having a large proportion of adult listeners--
about 50%, according to Ovaltine. The shows were generally well written and
well acted.
A radio premium served a double purpose it generated demand for the
sponsor's product and acted as a barometer of the show's popularity.
Like many other shows of the period, Captain Midnight gave premiums to
listeners. A radio premium was an item that served a double purpose: it
generated a demand for the sponsor's product (you had to send in a box top
or label or some such) and it acted as a fairly good barometer of the
number of people listening to the show (premiums cost less than the Hooper
rating service of the period). Many of the premiums were rings, such as the
Jack Armstrong Magic Dragon's Eye Ring, the Green Hornet Seal Ring, and the
Sky King Teleblinker Ring, and the Captain Midnight show sent out its
share. But Captain Midnight also distributed the Code-O-Graph, which was a
very special premium. See:

To understand the particular significance of the Code-O-Graph, it's
necessary to tell a little about the show. The central character was
Captain Midnight, the code name of a man who, as a young officer in World
War 1, had completed a dangerous and extremely important mission at the
stroke of 12. During the last few months of 1940, this fellow was brought
out of an early retirement to head a secret paramilitary organization that
would combat acts of sabotage. Captain Midnight was an aviator, and his
outfit relied on fast transportation, especially airplanes, to get to
out-of-the-way spots quickly. His outfit was called the Secret Squadron,
and it sent secret communications-first codes, later ciphers. And the
Code-O-Graph premiums let listeners in on the secrets.
A code is a symbol or group of symbols that represents a word or phrase.
The signal SOS means "I am in trouble and need assistance" and is thus a
code signal, though not a secret one. Codes may be symbols, such as a
skull-and-crossbones label on a bottle representing "the contents are
poisonous," or may be strings of letters.
To create a code scheme that enables agents to communicate meaningful
messages requires a lot of phrases and a lot of unique symbols. This
results in a code book, a rather bulky document used to encode and decode
communications.
The problem with a code book is that it's not the sort of thing a field
agent in the Secret Squadron could use as a practical matter. Such a book
would be too awkward for an agent to use, and would be relatively easy to
capture. As Captain Midnight said on the show, "We've got to have . . .
something small enough to be carried in a pocket and to be hidden easily.
And something that can be gotten rid of in a hurry, if you have to." He
brought the problem and a suggestion to Ichabod Mudd, the Secret Squadron's
chief mechanic, and the result was the first Code-O-Graph, a cipher device.
A cipher is what many laymen think of when someone speaks of a code. Unlike
a code, a cipher is a letter-by-letter substitution of characters in a
message. There are several varieties, but one of the most straightforward
is the substitution cipher.
JULIUS CAESAR'S CODE
A simple example is to take the alphabet and assign each letter its
positional number, so that A = I, B = 2, C = 3, etc. With this arrangement,
"code" is 3-15-4-5 . Of course, instead of numbers, it is possible to use
another set of letters. If we shift the alphabet three letters, we find
that A = D, B = E, and so forth, until we get to Z=C. In this scheme,
"code" would be "frgh." This particular cipher, incidentally, was used by
Julius Caesar, and is known to cryptologists as a "Caesar substitution" in
his honor.
The idea of shifting one alphabet with respect to another could be carried
to its logical conclusion by placing the two alphabets (or one alphabet and
series of numbers) on two disks, each divided into 26 arc segments along
its periphery, and connected by a central pivot. By moving the disks in
relation to each other, one scale could be repositioned relative to the
other. This device, known as a cipher disk, was invented by Leon Battista
Alberti in the mid-15th century.
The first Code-O-Graph had an inner dial with letters and an outer dial
with numbers from I through 26. The two scales could be repositioned by
turning the inner dial (technically, a rotor). The positions of the two
scales were determined by aligning a number located on the reverse side of
the rotor with one of two windows on the back of the Code-O-Graph. There
were several such numbers, and each window was labeled- one was "Master
Code," the other, "Super Code. " The alphabet was scrambled, as were the
alphabets on all subsequent Code-O-Graphs. All of them were cipher disks.
The first (or 1941 ) Code-O-Graph looked like a law-enforcement badge. A
listener could get one merely by sending a top seal from a can of Ovaltine
to the company, along with his or her name and address. By return mail, he
or she would receive a Code-O-Graph and a manual explaining various secret
signals. Getting a Code-O-Graph meant that the listener became a member of
the Secret Squadron.
Besides belonging to an "in" group, a listener with a Code-O-Graph could
decipher clues broadcast during "signal sessions."
What was the advantage in being a squadron member? Besides the general
feeling of belonging to an "in" group, a listener with a Code-O-Graph was
set apart because two or three times a week, the show would feature a
"signal session," in which a message in cipher would be broadcast. The
member with a Code-O-Graph would be able to decipher the message and obtain
a clue about the following adventure (particularly useful with a
cliff-hanger).
The second Code-O-Graph was manufactured in late 1941, but was not issued
until after the attack on Pearl Harbor (interestingly, in the show Captain
Midnight was in Hawaii in November of 1941, investigating the possibility
of an attack). This second unit had a more aeronautical design: a propeller
and radial aircraft engine design decorated the center of the rotor, and an
American flag motif graced the rest of the badge. The badge had a place for
the listener to put a picture of him- or herself, thus personalizing the
Code-O-Graph.
The 1942 model, like its predecessor, was undated, and had a window on its
back so that a number on the reverse of the rotor could be aligned for a
code setting. The second Code-O-Graph used a single window labeled Master
Code.
The acute shortage of materials during 1942 and 1943 precluded manufacture
of Code-O-Graphs for the years 1943 and 1944. In fact, most of the premiums
offered by Ovaltine and other sponsors were made of cloth or paper.
By late 1944, materials were not as scarce as previously, and Ovaltine was
able to offer a Code-O-Graph for 1945. The unit was made out of stamped
sheet steel coated with gilt paint (brass, which was used for the first two
Code-O-Graphs, was still a critical material). The rotor was made of
plastic. The year was prominently displayed across the top of the badge.
The decoration, which was more subdued than in the previous model,
represented a radial aircraft engine.
676 SETTINGS POSSIBLE
The cipher setting scheme was different. Instead of a window in the back
for scale alignments, the rotor was turned until a specific number was
aligned with a specific letter (e.g., "code Z7" meant that the rotor was
turned until the Z was next to the 7). The manual correctly stated that
this scheme enabled the user to have 676 possible key settings.
The center of the plastic rotor was molded to form a lens; the rotor was
made out of clear plastic, with its scale painted for easy readability.
This lens was a reasonably powerful magnifier, and the manual was dotted
with tiny messages that could only be read under magnification. Such
"unreadable" messages formed another type of secret communication.
The following year produced a very good-looking Code-O-Graph. The 1946
model was also dated, but not as obviously as the 1945 version. It, too,
used the letter-number key for code settings, and because the war had
ended, it was made of brass (except for the rotor).
The rotor was made of two plastic elements, a scale in red plastic (painting
clear plastic red hadn't been an optimum solution, experience with the 1945
model had shown) and a central clear element for a dial handle to turn the
rotor assembly. Behind the clear plastic face was a polished steel mirror,
which could be used for flashing signals to other Secret Squadron members.
The 1947 Code-O-Graph was a radical departure from the previous models in a
couple of ways. First, it was not a badge, but a police-type whistle. The
cipher scales were embossed and attached to one side of the whistle, while
the year date and the Secret Squadron symbol (a winged clock face with the
hands pointing at 12) were on the other side. The body of the whistle was
blue, while the rotor was red. This was the only radio-era Code-O-Graph
made entirely of plastic. Like the 1945 and 1946 Code-O-Graphs, it used
letter-number key settings.
The manual that accompanied the 1947 model suggested that the unit could be
used as a sound signaling device, and gave a number of whistle-signals
(such as those used by steam locomotives) for squadron members to practice.
The 1948 Code-O-Graph seems to have been designed by a committee. It was a
circular thing, similar in shape to a woman's compact. The body was brass,
with both the rotor and the outer scale movable by an aluminum knob in the
center of the face. The face was decorated with the date and a Secret
Squadron symbol, and the letter and its associated number were read through
small circular windows.
The rotor and outer scale were embossed on aluminum disks. Turning the knob
caused the two disks to turn; they were held together through friction
augmented by circular lines of dimples. The key setting was reminiscent of
the first two Code-O-Graphs: with the back removed, the user could set a
pointer at any of 26 numbers on the back of one disk, and this would change
alignment of the two scales.
Unfortunately, this unit didn't work very well. The friction dimples were
imperfect, and there was often slippage between the two disks. This of
course could change the key setting in the middle of a message, making the
remainder hash.
The red plastic back of the 1948 Code-O-Graph had a secret compartment that
could hold small pieces of paper or microfilm. Affixed to this compartment
was a steel mirror, rectangular and larger than the 1946 unit's mirror. The
red plastic back was subject to warping, and even archival copies of this
Code-O-Graph in the Ovaltine files have warped backs. Many of the mirrors
were lost before the year was out.
Mostly because of the flaws in the 1948 model, the last Code-O-Graph of the
radio series dispensed with frills and concentrated on ensuring that the
cipher setting, once made, would be maintained. The 1949 model was known as
the Keyomatic Code-O-Graph because it required a small key to change cipher
settings.
The unit is a small, oblong device about two inches long, consisting of a
brass housing containing two red plastic gears. One gear has the alphabet
scale embossed on it and the other has the number scale. Over the
number-scale gear is a small opening designed so that a little brass key
can be inserted into it. The number-scale gear is supported by a spring,
and inserting the key depresses the gear so that it disengages from the
other.
The 1949 Code-O-Graph used the letter-number cipher-key settings from the
1945,1946, and 1947 models. Like the 1948 model, the user could view only
one letter number pair at a time, through small windows on the face of the
unit. To set the 1949 model for master code B-6, for example, the user
would turn the gears by moving the exposed teeth of the alphabet-scale gear
until the number 6 appeared in the right-hand window. Then, using the key,
the user would depress the number gear, disengaging the two and retaining
the 6 setting. The alphabet-scale gear would then rotate freely, and the
user would move it until the B appeared in the left-hand window. Then the
key would be withdrawn, reengaging the gears.
While it offered a certain level of security to the unit, the key was
small, and easily lost. The manual that came with the Code-O-Graph
suggested that a string be looped through the key, but that wasn't done
often enough, and many members of the 1949 Secret Squadron had to learn
another way to reset their Code-O-Graphs. Since the key was not fancy, a
strong toothpick or an unbent paper clip could usually do the trick.
The 1949 model was the last of the radio-program Code-O-Graphs, and the
reason for this is that the program changed format. After the spring-summer
segment of the 1949 season, the program went from a 15 minute nightly
adventure serial to a program that was a half-hour in length, with a
complete story per episode. This was done in part because competing shows
such as Sky King had changed to the format successfully. With all the loose
ends tied up by the end of the show, however, there was no reason to send
secret messages, or so the show's producers thought.
And without secret messages, there was no need to issue a new Code-O-Graph.
So, the era of cryptography on commercial radio effectively came to an end.
Interestingly, the radio show did not survive long without its
Code-O-Graphs. The level of writing slipped to a simpler style, (perhaps
because everything had to be wrapped up in half an hour) and that alienated
the adult audience. Also, the actor who played Captain Midnight for a
decade, Ed Prentiss, had been replaced. And, of course, there was
television, which by 1950 was becoming a force to be reckoned with.
There were, no doubt, a lot of reasons for the show's demise. But I think
one of the main ones was that the day of the Code-O-Graph had passed.
Stephen A. Kallis Jr. is the author of a biography on Captain Midnight titled
Radio's Captain Midnight: The Wartime Biography (2000). The above article, written
by Kallis, first appeared in the February 1983 issue of Datamation Magazine.